Delimitation and, to a certain extent, demarcation of Iran's international boundaries date back to the early years of the 19th century. This was the time when frontier-consciousness was awakened in Iran as a result of the impact of the fateful Napoleonic wars in Europe and early contacts between Iran and the West. Before then, frontiers were vaguely based on the extent of sovereignty of the central government over the vassals of the border areas and the authority of the latter over their domains. Traditionally, such vassals were entrusted with the responsibility for guarding the frontiers against neighbouring countries.